Opinions about Aboriginal settlement of Australia in general, and of Northern Australia in particular, are currently in a state of flux. Because Australia had no primate stock, people must have migrated to the continent from elsewhere.
Until recently, the oldest firm date for Aboriginal occupation of Australia - obtained at a site on the Swan River, W.A. - was 38000 BP (before the present). The earliest dates from the Northern Territory were from Kakadu National Park in the Top End and from the Cleland Hills in the arid centre, and were in the area of 20000 BP to 25000 BP.
However, findings published in May 1990 by Drs. Mike Smith and Rhys Jones of the Australian National University show that these dates were far to conservative. Their work in Kakadu National Park has provided occupation dates at least 50000 BP; they suggest that initial occupation of the Australian continent occurred in the period of 50-60000 BP. These revised dates have resulted from improved dating techniques. Until recently carbon dating was the main method used, but this of limited use for dating beyond 25000 years.
A new technique, thermo-luminence, now allows dating of artifacts found in the lower levels of archaeology digs. While the timing and nature of the Aboriginal occupation of northern Australia is still debated, there is growing preference among prehistorians for what is termed the "porous northern perimeter" model. According to this model, occupation occurred as a result of steady migration rather than sudden waves.
T here is also evidence that environments that are extremely arid today - such as Central Australia - were far moister 20000 years ago, making them far more suitable for human occupation.
AUSTRALIAN ABORIGINAL PREHISTORY